Melt butter in large sauce pan. Add turtle meat and cook until it starts to brown. Add the vegetables and seasonings, continue cooking until the onions are translucent and the vegetables start to brown. Add canned tomatoes with their juices and continue cooking scraping up an bits stuck to the bottom of the pan. Pour into a crock pot. Return pan to heat and add beer, cook off any remaining bits stuck to the pan and pour into the crockpot along with the chicken stock. Cook on high for 6 hrs or low for 8 hrs.